Currently, the process of killing fish is carried out by means of a bump to the head of the fish, which can be performed by manual or pneumatic mode, in order to stun it and reassure the fish. Alternatively, cold solutions can be used as a method of slumber. Following the stunning, using a knife and manually, the gills or the aorta of the fish are cut, inserting the knife in between the operculum (which functions as a protective gill cover), in order to avoid damage on the outside of the fish. This method requires intensive labor and is usually performed during long work hours, which results in, when the operators have been working for a certain time, the possibility of cuts wrongly performed.
On the other hand, there are equipments consisting of a pneumatic puncher and a knife to cut the gills and/or aorta. Nevertheless, these have a major constraint for the industry, which is related to the damage on the outside of the fish produced by inaccurate or poorly designed cutting when inserting the knife to cut the gills. In these cases, a mechanical cut is made in the part of the operculum, leaving a visible cut that significantly reduces the quality and commercial value of the fish.
An example of this is disclosed in patent CA 02254436, which discloses an apparatus and method for slaughtering fish, comprising: means defining a predetermined path, enabling channeling the displacement of the fish; means for interrupting the movement of the fish at a predetermined position along said path; capture means to keep the fish in the predetermined position; means to stun the fish; means to kill the stunned fish; and means for releasing the dead fish. However, the apparatus described in this document exhibits very low versatility in fish morphology to be slaughtered, since it requires calibration to slaughter fish of different sizes; i.e., the apparatus can be configured only to slaughter fish with a homogeneous morphology.
Another similar solution is described in the patent application PCT/IB2010/053671, of the same inventor as the present invention, in which an apparatus for processing fish with self-regulation mechanism according to the morphology of the head of the fish is disclosed, which comprises an assembly to stunning the fish to be processed, a support assembly and a stunning piston assembly; a central assembly comprising a housing, a guide assembly for the input and processing of fish and comprising a lower guide plate, a trigger assembly that triggers the stunning piston assembly and an adjuster assembly which position varies depending on the size of the fish to be processed; a cutter assembly to cut gills or aorta located below the housing; and a pneumatic circuit which connects the trigger assembly, the stunning piston assembly and cutter piston, wherein the trigger assembly activates the pneumatic circuit, said stunning piston and said cutter piston.
However, the apparatus described above depends heavily on operator interaction in the process of slaughtering fish, since it depends on an operator that must enter the fish to the apparatus, hold it as the apparatus slaughters the fish, and remove it manually to continue with the slaughtering process.
Notwithstanding the abovementioned disadvantages, the major limitation of the prior art, which can be clearly appreciated in both documents, corresponds to the existing equipment causing a longitudinal cut in the bottom of the fish, thereby cutting the aorta and/or the operculum, which results in an undesirable visual appearance in the fish, thus causing a devaluation of the fish as a product on the market as being regarded as an inferior product.
Consequently, it can be seen in the prior art that there is a need for an apparatus for slaughtering fish, which allows stunning and killing the fish quickly and accurately, regardless the morphology of the fish, in a manner that prevent skin damage visually perceptible thereof, and enabling at the same time having a high level of automation, in order to minimize the interaction of an operator In the process.
To overcome the problems an apparatus to slaughter fish is provided, causing the death of fish by taking it from the operculum to be positioned in a stunning position, then cutting the gills without causing any visible damage to the outside. Thus, the apparatus comprises:                positioning means for holding and positioning the fish at a predetermined position;        detection means for detecting the positioning the fish and to stop the movement thereof in the predetermined position;        gripping means to take the fish from the operculum and position it in a stunning position, which also allows the opening of the operculum so as to leave the gills exposed;        stunning means to stun the fish that is held from the operculum;        cutting means that cut the gills of the stunned fish in a way that its bleeding occurs without cause external damage; and        releasing means to release the dead fish from the apparatus.        
Thus, by means of the described apparatus for slaughtering fish, it is possible to stun and kill fish quickly, efficiently, and without causing damage to the external appearance of each fish, since the gripping means allow to position and expose the gills, so that an accurate cut is made, without causing cuts in other unwanted areas.
Moreover, given the configuration of the invention, the apparatus is capable of slaughtering fish with minimal intervention of the operator, since the apparatus allows gripping, positioning, stunning and killing the fish, so that the process can be continued without operator input, due to the releasing means of the apparatus. Thus, the operator must only enter eventually the fish into the apparatus, where the fish will be fished automatically, and it could even dispense with the operator if known means in the prior art that, allowing entry and direct the fish towards the apparatus are used.